In this study, the effectiveness of prolonged dry-heat treatment (50 degrees C) alone or in combination with chemical treatments (1% oxalic acid, 0.03% phytic acid, 50% ethanol, electrolyzed acidic water, and electrolyzed alkaline water) in eliminating Escherichia coli O157:H7 on laboratory-inoculated alfalfa, radish, broccoli, and mung bean seeds was compared with that of dry-heat treatment in combination with irradiation treatment. Dry-heat treatment for 17 or 24 h alone could reduce E. coli O157:H7 numbers to below detectable levels in radish, broccoli, and alfalfa seeds, but was unable to reduce the pathogen numbers to below the detectable level in mung bean seeds. In addition, dry-heat treatment for 17 h plus sanitizer treatments were effective in greatly reducing pathogen populations on radish, broccoli, and alfalfa seeds, without compromising the quality of the sprouts, but these treatments did not eliminate the pathogen from radish and alfalfa seeds. Seventeen hours of dry heat followed by a 1.0-kGy dose of irradiation completely eliminated E. coli O157:H7 from radish and mung bean seeds, whereas only a minimum radiation dose of 0.25 kGy was required to completely eliminate the pathogen from broccoli and alfalfa seeds. Dry heat in combination with radiation doses of up to 1.0 kGy did not negatively impact the seed germination rate or length of alfalfa, broccoli, and radish seeds or the length of alfalfa, broccoli, and radish sprouts, but did decrease the length of mung bean sprouts.

The majority of the seed sprout-related outbreaks have been associated with Escherichia coli O157:H7 and Salmonella. Therefore, an effective method for inactivating these organisms on the seeds before sprouting is needed. The current pasteurization method for mung beans in Japan (hot water treatment at 85 degrees C for 10 s) was more effective for disinfecting inoculated E. coli O157:H7, Salmonella, and nonpathogenic E. coli on mung bean seeds than was the calcium hypochlorite treatment (20,000 ppm for 20 min) recommended by the U.S. Food and Drug Administration. Hot water treatment at 85 degrees C for 40 s followed by dipping in cold water for 30 s and soaking in chlorine water (2,000 ppm) for 2 h reduced the pathogens to undetectable levels, and no viable pathogens were found in a 25-g enrichment culture and during the sprouting process. Practical tests using a working pasteurization machine with nonpathogenic E. coli as a surrogate produced similar results. The harvest yield of the treated seed was within the acceptable range. These treatments could be a viable alternative to the presently recommended 20,000-ppm chlorine treatment for mung bean seeds.

The majority of seed sprout-related outbreaks has been associated with Escherichia coli O157:H7 and Salmonella. Therefore, it is necessary to find an effective method to inactivate possible pathogenic bacterial populations on the seeds prior to sprouting. In general, sanitizing is more effective in reducing contamination on seeds than on sprouts. A successful seed decontamination treatment must inactivate microbial pathogens while preserving seed viability, germination, and vigor. Seeds vary in sensitivity to antimicrobial agents and other treatments, which determine how well they germinate and grow after treatment. In addition, a treatment that is effective for one type of seed may not be applicable to all types of seeds. Seeds vary in surface features, which may influence how well an antimicrobial agent can access and inactivate pathogens on or in the seed. The use of a number of physical, non-thermal processing technologies, alone or in combination with antimicrobial chemicals, could be useful for seed decontamination. Until now, hot water treatment at 85°C for 40 seconds followed by cooling in cold water for 30 sec and soaking in chlorine water was found effective in inactivating pathogens while preserving seed viability, germination, and vigor. Therefore, hot water treatment could be an effective seed decontamination method for mung bean seeds intended for sprout production.

The majority of seed sprout-related outbreaks have been associated with Escherichia coli O157:H7 and Salmonella. Therefore, we aimed to find an effective method to inactivate these organisms on seeds before sprouting. Treatment with 8.7% (v/v) acetic acid at 55°C for 2-3 h reduced the population of E. coli O157:H7 and Salmonella inoculated on alfalfa (Medicago sativa L.) and radish seeds (Raphanus sativus L.) by more than 5.0 log CFU/g, and a longer treatment time completely eliminated the E. coli O157:H7 population. The E. coli O157:H7 populations were reduced to an undetectable level with a gaseous acetic acid treatment for 48 h. After enrichment, no E. coli O157:H7 were found in the alfalfa and radish seeds (25 g). However, these treatments were unable to eliminate Salmonella in both seed types. No significant difference between the germination rates of treated alfalfa seeds and control seeds was found, and germination rates greater than 95% were obtained for the radish seeds. Although chlorine washing is commonly used for seed decontamination, chlorine washing at 200 and 20,000 ppm resulted in a reduction of pathogens by less than or equal to 3 log CFU/g. Therefore, these results suggested that gaseous acetic acid is more effective than chlorine washing in controlling pathogenic bacteria on sprout seeds.

Several pasteurization procedures for alfalfa (Medicago sativa) seeds were investigated to completely disinfect inoculated Escherichia coli (Migula) Castellani and Chalmers ATCC(25922). Hot-water treatments (85˚C for 9 s) were equally or more effective than 20,000 ppm calcium hypochlorite treatments, yielding a reduction of 2 log 10 CFU/g. A greater reduction (4 log) was obtained by soaking the seeds prior to the heat treatments and, in some cases, no inoculated bacteria were detected after enrichment of the seeds in peptone. No survival of inoculated bacteria was detected from the seeds or the sprouts after deeply presoaking (15˚C for 60 min) and treating the seeds with heat, but the germination decreased to 73% along with the yield which fell to 78.4% that of the control. We describe the hot-water treatment as an alternative method to hypochlorite treatments for disinfecting pathogenic bacteria in seeds for alfalfa sprout production.

A majority of the seed sprout-related outbreaks have been associated with Escherichia coli O157:H7 and Salmonella spp. Therefore, it is necessary to find an effective method to inactivate these microorganisms on the seeds before sprouting. When treatment with hot water at 85 degrees C for 40 sec followed by dipping in cold water for 30 sec and soaking into chlorine water (2000 ppm) for 2 h was performed, no viable pathogens were found in the enrichment medium and during the sprouting process. The germination yield of the seed was not affected significantly (p > 0.05). Therefore, these treatments could be useful for the decontamination method of mung bean seeds intended for sprout production.

No abstract

The calli were induced from the pistils of saffron. MS, 1/2 MS, and NN medium with BA and NAA at 1 mg/l each were the most effective for the induction and growth of the calli. The calli produced crocin, crocetin-di (monoglucosyl-diglucosyl) ester and crocetin-di (monoglucosyl) ester. The calli producing those pigments have been maintained for more than two years under dark conditions. Saffron, Crocus sativus L., was originated from south Europe and has been recognized for its medicinal properties for a long time. The serum cholesterol levels of rabbits were reduced by half after intra muscular injection of crocetin. 1) Its principle value, however, now is as a food spice and colorant.2) The main pigments of saffron are mono-and diglycosyl esters of crocetin. Besides these crocetin derivatives, small amounts of a-carotene, B-carotene, lycopene and zeaxanthin have been isolated.3) The cultivation of saffron and harvesting of pistils require intensive labor.We have tried to produce color and medicinal compounds from callus derived from the pistil of saffron in vitro. Here we show the induction of callus from saffron, Crocus sativus L. and the pigmentation. Materials and MethodsBulb of saffron. The bulb of saffron was purchased from a local market and sprouted at room temperature under the natural sun beam. The sprouts sized 3-5 cm were cut with a blade and sterilized by dipping into 70% ethanol 2-3 times. The sheaths of the sprouts were removed and the pistils collected from the sprouts. The pistils were cut about 5 mm long from the top of the stigma and used as explants. Six explants were placed onto the 10 ml of agar medium in a disposable plastic petridish.Culture of explants. The explants were cultured for three months under the continuous illumination of fluorescent lamp at 3,000lx at 20C. The callus induction was checked with a microscope at one month after the inoculation. The growth of the callus were checked with the naked eyes at three months after the inoculation.The explants were also cultured in a flask containing 5 ml of liquid media listed in Table 2 and gyrated at 100 rpm.Maintenance of the callus. Three months after the initiation of culture, half of each callus was maintained by changing the agar medium every three months under light conditions. The rest of the half was kept in the dark. When the callus was placed onto the new medium a part with no color was removed by cutting with a blade. Since no difference in color was observed between the calli maintained under the dark and that in light conditions for one year, all calli have cur-